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ASAS-SN Discovery of A Probable Supernova in An Unknown Redshift Galaxy GALEXASC J011659.34-045630.6

ATel #8471; K. Z. Stanek, J. S. Brown, T. W.-S. Holoien, C. S. Kochanek, D. Godoy-Rivera, U. Basu (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong, Ping Chen (KIAA-PKU), J. Brimacombe (Coral Towers Observatory)
on 29 Dec 2015; 19:22 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

Subjects: Optical, Supernovae

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered a new transient source, most likely a supernova, in the galaxy GALEXASC J011659.34-045630.6.

ASASSN-15uo was discovered in images obtained on UT 2015-12-29.06 at V~16.7 mag, and we also detect the object in images taken on 2015-12-27.07 (V~16.8). We do not detect (V>16.7) the object in bright-Moon images taken on UT 2015-12-25.09 and before. This figure shows the archival DSS image of the host (left), the ASAS-SN V-band reference image (middle), and the ASAS-SN subtraction image (right) that was used to discover the supernova candidate. The red circle has a radius of 5" and is centered on the position of the transient in the subtraction image.

The position of ASASSN-15uo is approximately 12" from the center of the galaxy GALEXASC J011659.34-045630.6 (no redshift information available from NED, foreground reddening A_V=0.12). Properties of the new source and photometry are summarized in the tables below:

Object       RA (J2000)     DEC (J2000)      Disc. UT Date   Disc. V mag  Approx. Abs. Mag   Offset from Host (")  
ASASSN-15uo   01:17:00.00   -04:56:34.1      2015-12-29.06     16.7          N/A                 12  
Obs. UT Date        V mag  
2015-12-25.09      >16.6  
2015-12-27.07       16.8   
2015-12-29.06       16.7  
Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported by NSF grant AST-1515927, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, the Mt. Cuba Astronomical Foundation, and the Robert Martin Ayers Sciences Fund. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.